But after all my tests, i need your advices/help on three particular points :

1) What software do you use for online backup ?

2) All sites advice to make the first full backup on the LAN (obviously)... then, incremental backup over WAN will occur... But, when comes the time to run the 2nd full backup, how do software backups work ? I hardly can imagine that it simply backups all the files without any particular software technology... My friend said me that it *seems* to him that BackupPC, when running a full backup, does like a incremental backup and then use it to *generate* a full backup on remote server-side... I'd like confirmations and, by the way, i didn't managed to reproduce it with Areca Backup (it stupidly reupload all the entire data)...

3) An obvious function that my friend didn't manage to have it working : backup resume... In fact, during some days, backup tasks weren't running... when backup day came, a lot of data needed to be backup... But, with its poor adsl line, the backup was always interrupting and BackupPC was always restarting its backup from scratch (partial backup getting deleted)...
After seeing that Areca seemed to have implemented it ( http://sourceforge.net/tracker/index.php?func=detail&aid=1995529&group_id=171505&atid=858191 ), i decided to try it... without success... Strangely, a feature request keeps opened despite of the previous same request being declared fixed (resume function) ( http://sourceforge.net/tracker/index.php?func=detail&aid=2672134&group_id=171505&atid=858194 )... Do the software you use, has resume function or auto-resume after backup interrupting ? Indeed, i can't imagine online backup without this function....

Well, thank you very much, if you've read all the text until here ....

In other words, which backup software can :

* Generate full backup from previous backups + delta data

* Auto-resume backup when interrupts occur

(I hope there's at least one !... If not, it means that all actual backup software are usefulless...)